FIX: Searchable user fields do not always have an integer name (#30223)

spec/models/user_custom_field_spec.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+RSpec.describe UserCustomField do
+  describe ".searchable" do
+    it "includes user_custom_fields with valid, searchable user_field references" do
+      Fabricate(:user_field, id: 123, searchable: true)
+      valid_user_custom_field = Fabricate(:user_custom_field, name: "user_field_123")
+
+      result = UserCustomField.searchable
+
+      expect(result).to include(valid_user_custom_field)
+    end
+
+    it "excludes user_custom_fields with non-searchable user_field references" do
+      Fabricate(:user_field, id: 456, searchable: false)
+      non_searchable_custom_field = Fabricate(:user_custom_field, name: "user_field_456")
+
+      result = UserCustomField.searchable
+
+      expect(result).not_to include(non_searchable_custom_field)
+    end
+
+    it "excludes user_custom_fields with invalid user_field references" do
+      invalid_user_custom_field = Fabricate(:user_custom_field, name: "user_field_invalid")
+
+      result = UserCustomField.searchable
+
+      expect(result).not_to include(invalid_user_custom_field)
+    end
+
+    it "excludes user_custom_fields with unrelated names" do
+      unrelated_custom_field = Fabricate(:user_custom_field, name: "cost_center")
+
+      result = UserCustomField.searchable
+
+      expect(result).not_to include(unrelated_custom_field)
+    end
+  end
+end